Tracking the Islamic State’s rise

In recent months, the Islamic State has been establishing a foothold in Iraq. The group swept in from Syria and captured a number of key areas, including Mosul, Iraq's second largest city. In addition to putting American personnel at risk, the IS has led a bloody campaign against religious minorities. Thousands of Yazidis refugees remain trapped in the Sinjar mountains with dwindling supplies of food and water. The U.S. has since begun launching airstrikes against the militants. But how did the conflict come to be? A look at the situation: